Title: The Physics of Playing French

Horn

Name: Bethany Deibler

Date: May 30, 2008

Spring quarter

Class: Physics 100

Sidibe, 9:10

WORKING TOWARD: A

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The French horn is a unique instrument. It is included in both the brass and woodwind categories

of instruments. It is one of the largest instruments as a double horn is up to 24 feet long when unraveled.

Another common question about the French horn is whether it is actually French or not. The British

originally had a hunting horn. The French also had a horn that was similar, but larger and used typically

for actual music production, not just hunting. However, these two instruments were very similar and the

names for them are interchangeable. In fact, the issue about whether the horn is actually French is

debated. In Europe, they are simply called horns and here in America we call them French horns. Another

theory is that the horn originated in the Alps and Germanic countries for protecting flocks. These

mountains were mainly populated by French people, thus the French horn.

The original horn did not have any valves. The notes were far apart and harsh sounding. This is

because of the original use for the horn, which was hunting. There were many different variations of the

horn used for a variety of different things. Some were used in battle; others were used in protecting

flocks, and still others for hunting. Since the 17th century, the round shape has been the same. However,

there have been valves added as well as more slides. Originally, before valves, a horn player had to switch

out the slides of different lengths to get different pitches. This was very inconvenient for playing the horn

as a musical instrument in concert.

A French horn consists of four main parts; the bell, the valves, the lead pipe, and mouthpiece, as

well as the slides. Each one plays an important part in making a beautiful tone. A fascinating thing to

think about is the fact that these parts function the way they do because of physics. I will look at how

each part works along with the physics of the instrument.

As an instrumentalist, there are three qualities of sound that are of interest; pitch, loudness, and

quality. All of these require using air. Air is the most important part of playing the instrument. Without air

there is no sound. With a little bit of air, there is a poor sound. But with a lot of air, a good pure tone can

be produced.

What makes the sound?

In order to have sound, we must start with a vibration. This vibration is in the lips of the player.

Sound is produced by an oscillating motion or air flow. Contrasting with random noise, a tone or musical

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note has a constant wave for motion. Noise is not a constant sound wave.

When a tuning fork is struck, sound waves are produced. Sound waves are caused by vibrations.

They follow either a sine or cosine pattern. These waves are directly related to the frequency of the sound.

The oscillatory motion that the air makes through the mouthpiece is similar to the movement of a

pendulum swinging back and forth. The length apart of each period is directly related to the frequency.

Frequency = 1/period. It is also called simple harmonic motion. The amplitude of a sine way is the

distance from the midpoint to the crest of the wave. The wavelength is the distance from the top of one

crest to the top of the nest. By wave motion, we can see light and hear sounds. It is energy transferred

from one source to another. When the waves stop, the air particles return to their original position. Wave

speed = wavelength * frequency. This relationship can be used for all types of waves.

Transverse waves are sideways motions, perpendicular to the wave. The strings on stringed

instruments move in transverse waves. There are also longitudinal waves. These are waves that move

along the direction of the waves, not at right angles of the direction. These are sound waves.

The air inside an instrument must vibrate and be at a pressure higher than the normal atmosphere

to produce a sound. The bell resonates with the sound that is produced by a steady stream of air. Certain

notes have certain pitches or frequencies. Frequencies are measured in Hertz after Henry Hertz. He was

the first to discover radio waves in 1886. One hertz is equal to one vibration per second. A common

frequency to tune instruments to is the note A which is a frequency of 440 Hz. A piano’s A key hits the A

string which then vibrates 440 times per second. A note one octave below that would be 220 Hz. Humans

can hear from about 10 Hz. to 20,000 Hz. or 20 KHz. Sounds less than 20 Hz are called infrasonic waves

and more than 20,000 Hz are called ultrasonic waves.

How does sound travel through air?

Air is a relatively poor conductor of sound. Other materials are much better for conducting sound.

In fact, sound travels four times faster in water than in air and about fifteen times faster in steel than in

air. In general, the speed of sound is greater in solids than in liquid and greater in liquids than in gases.

The speed of sound also depends on the weather conditions. Things such as temperature, wind, and

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humidity effect how fast sound travels. All levels of sounds travel at the same speed, no matter how loud

or soft they are. In a condition where there is zero moisture in the air and 0 degrees Celsius, sound travels

about 330 meters per second, which is about 1200 kilometers per hour! Moisture increases the speed of

sound as well as warm air. For each degree that the temperature is raised, the speed of sound increases by

0.6 meters per second.

Reflections or echoes are the reasons that we hear things. Sound reflects similarly to light. From a

smooth surface, the sound will reflect off of it with the same angle that is hit the wall. When there are

many reflections happening at the same time this is called reverberations. Acousticians use this when

designing halls to get the best quality of sound sitting anywhere in the auditorium.

Sound is also refracted by wind and temperatures. These waves get bent and travel in unnatural

paths. Different speeds of sound result in refraction. If it is a warm day, the air closer to the ground will

be warmer than the rest of the air. This will cause the sound waves to bend away from the ground causing

an inconsistency in the direction and speed that it is traveling. Sound also travels slower at higher

altitudes and goes away from the ground which is why we don’t hear thunder for storms that are far away.

However, on a cold day or at night when the air next to the ground is cold, sound waves are heard much

easier. Sound refraction underwater also depends on the temperature. Since the ocean is so many different

temperatures in different places, this creates a lot of inconsistency. This leaves gaps and places for

submarines to hide from detection.

How do you make different pitches?

Different pitches on the horn are obtained either by using the valves, or changing the air speed

and volume. The air that is blown through the instrument vibrates at some frequencies much easier than

other frequencies. These frequencies determine the pitch that comes out of the instrument. When the

player changed the length of the instrument, the pitch changes with it. With a French horn, when you push

down a lever, it changes the direction of the air flow into a pipe of a different length thus changing the

pitch. Larger instruments require more air, so more air is necessary to play notes with a good tone. A

weak tone is caused by a weak stream of air through the instrument.

Each note that can be played without pressing the valves is called a partial. There are some

partials that are easier to play than others. Each partial has its own frequency for it to be in tune. This is

also called a harmonic series. On a French horn, the harmonic series is fairly close together as a whole

scale can almost be played without using the valves. However, the notes are not always in tune in the

harmonic series. Some horns only use this harmonic series to play a piece. This is difficult and requires a

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lot of flexibility in the lips and ears to hear the tones that you want to sound. French horn is a more

difficult instrument to play than trumpet because the harmonics are so close together. Often during a

song, it is hard to tell which note is supposed to be played and it is easy to get on the wrong partial, a third

or a fifth away from the note that is supposed to be played. Each one of the horn’s harmonic series is an

odd multiple of 23Hz. These are: 23Hz, 69Hz, 115Hz, 161Hz, and more. The equation to come up with

these numbers is given by f = nv/4L. Where n is an odd number, the frequency equals n times the speed of

sound divided by 4 times the length of the wave. These are all the notes that can be played without using

the valves.

Horn harmonic series.

Horn players are renowned for missing notes and partials. This is because of all the notes that can

be played with one fingering. While many of these notes will be out of tune, they can all be played.

Another useful thing while playing the horn is bending the pitch. This is either making the notes a few

percent sharper or flatter and is done with the mouth or embouchure. If done rapidly, it is called vibrato

and adds a nice effect to a song.

How do the valves and slides work?

Most horns use rotary valves which simply rotate when the key is pushed to lead to a different,

extra length of tubing. The valves, when they are rotated, have holes in them that change the direction of

the air stream to a longer piece of tubing. The difference between each length of tubing changes the pitch.

This difference between the tubing is a certain percentage of the total length in order to lower the pitch by

a whole tone. To lower the pitch by a step, the second valve must add a length of tubing 5.9% of the total

length. By pressing both valves together, the length increases by 18.1%. However, to lower the pitch by

three semitones, an increase of 18.9% is required. In this case, we need 0.8% more tubing for the pitch to

sound in tune. For a horn player, it is necessary to move the hand to compensate for this difference in

pitch.

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There is also friction associated with the valves. For this reason it is necessary to use oil on the

valves. This will keep them from scraping the casing and ruining the horn. Slide grease is also necessary

to put on the slides so they will move in and out freely. This also reduces the friction and scraping that

can occur if the slides are not greased sufficiently. There is also compression with the slides. If the

instrument is not air tight, the slides can fall out and get dented. Both the slides and the valves themselves

should be air tight. The air inside the horn will keep the slides from falling out. Also, if the instrument

has a leak, some of the air that the player is putting into the instrument will leak out and the instrument

will not be at its maximum efficiency.

Slides are also used to tune the instrument. There are so many other ways to tune the instrument

that it depends on the player as to which method they like best. An instrument can be tuned by changing

the pitch with the mouth or embouchure, by changing the hand position, or by using the tuning slides.

Personally, I use the main tuning slide to tune one note and use my lips to bend the note one way or the

other. Even if the horn player does not use the tuning slides to tune, all of them should be pulled out at

least a half of an inch.

How does the bell affect the sound?

The French horn is designed to keep as much of the sound that is created inside the tube as is

possible. They were not designed for the radiation of sound. This is the job of the bell of the horn. The

bell works on both long sound waves as well as shorter sound waves to make them sound better. A wave

that is longer than the diameter of the tube is stuck in side and no sound comes out. If you add a bell to

the end of the tube, then it adds a gradual increase of diameter to make a sound. The bell has to increase

in equal amounts so the sound will come out. If the bell is too abrupt, the sound will stay stuck inside and

will not come out. The bell also solves the problem that the notes are too far apart to be musical and the

instrument is not very loud without it. The gradual increase of diameter is almost conical. Conical pipes

resonate at frequencies that are higher and more closely spaced than a closed cylindrical pipe, such as the

normal tubing used for the instrument. For low pitches, which resonate with long waves, the waves are

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longer and act differently than short waves through the bell.

For short waves, it is easier to travel out into the open air and escape the wide bell. Faster and

higher sound waves travel faster. Thus, you can easily hear a piccolo over a tuba. This is also why a

trumpet plays higher than a tuba. The size of the bell makes different frequencies easier to produce. These

pitches are in the range where our ears are most sensitive making brass instruments louder than

woodwind instruments. However, along with a high transmission of sound comes low reflection. With

low reflection, we get weak standing waves, weak resonances, and flexible notes. When any brass player

tries to play higher notes, the sound gets weak and is often extremely out of tune. The bell also means that

the instrument is directional. So, whichever direction the bell is pointing is the direction the sound will

go. This can be used to make different sound effects.

What does the hand do?

The hand in the bell is also important for the sound that comes out of the instrument. To get the

clearest tone from the instrument, the hand should be cupped and placed on the outside curve of the bell.

Otherwise, the tone will be altered. Without the hand in the bell, the horn will tend to be sharp. If the hand

is placed too far in the horn, the pitch will be flat and the sound will be muffled. There are also different

hand placements that are called for in certain songs to obtain different sounds. Stopped horn is played by

putting the hand further into the bell and stopping the sound. This requires much more air to get the

sizzling sound to come out. This also changes the pitch, so the player must finger the note one half step

higher than the note that is written. This is written in music with a + over the note. Mutes are also placed

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in the bell to get this same effect. However, mutes do the transposing part for the player so it can be

played as it normally would.

How does the mouthpiece, tongue, and lips effect the horn?

The mouthpiece of the horn is an important part of the instrument. It includes an enclosed

volume, constriction, and taper. The mouthpiece should fit comfortable on this lips of the player. Each

mouthpiece has certain pitch or pop it makes when hit on the palm of you hand. Different mouthpieces

have different sounds that are produced with it. The purpose of the mouthpiece is to have a large enough

section to put your lips on to play the instrument. It also has acoustic effects on pitches that are higher

than the pop pitch the mouthpiece makes. The enclosed volume and constriction are the two main parts

that affect this. It strengthens some of the higher resonances as well as lowers the frequency of the

extremely high resonances.

Lips are springy, as they go back to their original position after you move them. The story that

your mother gives you about your face sticking is fortunately untrue. Springiness and mass put together

can create oscillations which is what the lips do to produce sound. The air pressure in the mouth forces

the lips open and lets the air rush out into the mouthpiece. This then lowers the pressure in the mouth and

also lowers the pressure in the stream of air going out of the lips. The lips then close again due to their

elasticity and the pressure in the mouth builds up once again. The cycles then repeats.

The tension used on the mouthpiece is also important for the sound that is produced. The more

tension you apply to your lips, the more quickly they spring back into position. If the whole cycle takes a

time T (called the period), then there are (one second)/T cycles per second. So the frequency f, in cycles

per second, is just f = 1/T. High lip tension gives high frequency and thus creates a high pitch. This

however, is the incorrect way to play higher notes. If you tighten the lips, this creates a pinched sound.

The correct way is to use more air and not as much pressure.

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A mouthpiece makes relatively minor changes as it can reduce the amount of the lips that move,

and it allows the pressure outside the lips to be a little different from atmospheric. The best way to

position the mouthpiece is asymmetrically, so that it covers more of the upper lip than the lower lip.

The tongue is also important in playing the French horn. There are two ways to “tongue”. The

purpose of tonguing is to stop the sound. This can be accomplished by either stopping the air flow, using

the throat to stop the air flow or using the tongue to stop the air flow. The most convenient and useful

way of tonguing is by using the tongue to stop the air. This is much better for fast music. There are also

methods such as double and triple tonguing. This is when a combination of throat and tongue is used to

produce a very rapid succession of notes.

How do different metals affect the sound?

Some players prefer a brass horn while others prefer a silver horn and still others a lacquered

horn. Each metal affects the sound in a different way because of the different vibrating qualities of the

metals. There are lacquered horns, horns plated in gold or silver, and horns that are bare metal. Each

player has his or her preferences as to which horn they like better.

An experiment was done where three identical instruments were put in the three different

coatings. It was found that plain brass and silver or gold plated instruments played exactly the same.

However, a lacquered instrument changed the tone a bit. The tone was impaired and the over all pitch was

changed. This is because the lacquer is very thick on an instrument. It changes the quality and resonance

of the bell. It is unlike the original brass to begin with so the amount of lacquer that goes on the

instrument changes it to a new instrument with a non brass bell.

How is the loudness measured?

In written music, musicians are given certain loudness markings or dynamics to follow. A forte

(f) means loud, piano (p) means soft. Mezzo (m) is added to these to mean moderately, for example,

Mezzo forte (mf) means to play moderately loud. During these changes, the pitch does not change, just the

loudness that the note is being played. The change from loud to soft is called a decrescendo and a change

from soft to loud is called a crescendo.

The scientific way to measure the level of sound it with decibels (dB). dB is a logarithmic unit

used to describe a ratio of two measures of the sound. The ratio may be power, sound pressure, voltage or

intensity or several other things. In this case, we are measuring the amount of sound pressure. The

difference of one decibel is quite hard to distinguish, thus decibels are rarely measured in increments

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smaller than 1 dB. This can also be measured as the intensity of sound. 10 decibels is equal to 1 bel,

named after Alexander Graham Bell. This can also be written in the units, Watts per meter squared. To

make a crescendo noticeable during a piece of music, the musician must increase the sound by at least 8

decibels. However, in the higher range of notes, the difference is even harder to tell so the musician may

have to increase the sound by as much as 45 decibels. Decibels are also directly related to the atmosphere

and atmospheric pressure. While 120 dB can be a painfully loud level of sound, it may not be a problem

when the atmospheric pressure is different. To determine the loudness of a sound, one needs to consult

the curves representing the frequency response of the human ear. Loudness is measure by the amplitude

or height of the sine curve. Loudness and intensity are different however. Sound intensity is objective,

while loudness is a physiological sensation.

What is timbre and the quality of sound?

It is not difficult for people to tell the difference between a tuba and a piano. This is because each

instrument has its own quality or timbre. Each instrument, when it sounds one note, has a variety of other

notes that can be. A middle C on a piano is about 262 Hz. It also has a blend of other partial tones that

also ring at the same time. A pure tone with only one frequency can only be produced electronically. This

is how we can tell different instruments apart. If both a piano and a horn play a C, the horn will have

different frequencies ringing than the piano and will creating a different sound.

In order to get the best quality of sound on a horn, the lips need to be placed correctly with the

right amount of tension and the amount of air blown should be enough to produce a good sound. For the

lips and the mouthpiece, first you need to say the letter “m” This puts the lips in the best formation for

sound. Place the mouthpiece on the lips and blow air. There must be a vibration for the sound to come

out. A poor quality sound can be made by not enough air, too much tension in the lips, a restricted throat,

and very rarely, too much air. These problems can usually be solved by taking a bigger breath and

blowing more air through the instrument. This, as well as relaxing the throat and lip tension, will solve

most problems associated with tone.

What do I change when playing with an ensemble?

When an individual plays with other people, he or she has to listen to play in tune with the other

players. While a horn player may be in tune exactly, according to a tuner, he will probably be out of tune

with the other players in the ensemble. The pitches of each interval must a certain length apart in order to

sound good to our ears. For example, some chords are structured so that the third of the chord needs to be

played lower than usual for it to sound good to our ears.

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Also, when playing with other players, the sound levels are relevant to the rest of the band. A

forte in a solo piece will be much louder than a forte in a group of players. The dynamics are not a certain

decibel level, but a relative measurement. Playing with a piano accompanist is very different from playing

with a 40 instrument band.

With a band there are certain balances that sound best with each song. A pyramid of sound is

used in most tunes. This is where the low instruments like trombones and tuba are the loudest, and the

higher instruments, such as trumpets and flutes play softer. There are many different sound “shapes” that

can be made.

French horns are usually considered to be a part of the middle section

although, because of the large range of a horn, they can be included in the high and low ranges as well.

When two or more instruments are played together, the two different frequencies combine. While

on a picture of the frequencies, it is hard to tell them apart, our ears can distinguish the different sound

that each unique instrument makes.

The French horn is a unique instrument as most of the sound is directed to one side. For this

reason, it is important to put the bell closest to the audience for the best sound. Also, a horn player hears a

different balance than the director hears at the front of the ensemble. It is important for the player to listen

carefully to the balance of the rest of the band. However, horn players rarely are told that they are playing

too loud. Because of all of the tubing that horns have, it is more difficult to play loudly. Also, horns have

a more mellow sound than all of the other instruments making it more difficult to hear. It is often used as

an instrument to fill out the sound of the chord. It is felt in the music more than it is actually heard.

In conclusion, it is fascinating how everything we do has some sort of physics involved in it. We

rarely think about why and how things work the way they do. We always just take it for granted. This

paper has been very informational for me and has helped me understand my favorite instrument a little

better than before.

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BIBLIOGRAPHY

Author: Joe Wolfe

Title: Brass instrument (lip reed) acoustics: an introduction

Date of publication: Oct-Mar 2005

Place of publication: The University of New South Wales.

Website URL: <http://www.phys.unsw.edu.au/jw/brassacoustics.html>

Author: Matthew Panayiotou

Title: Articles - The French Horn

Date of publication: 2005

Place of publication: London

Website URL: <http://www.matthewpanayiotou.com/articles/fhorn/?page=4>

Author: Leah Norwood

Title: Horn Harmonics

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Place of Publication: California

Website URL: <http://www.hornharmonics.com/background.html?>

Author: Paul G. Hewitt

Title: Conceptual Physics, 10th edition

Publisher, place of publication, date of publications or copyright date: Published by Pearson Education

Inc. in United States of America, copyright 2006.

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